Rickard A.M.,Institute for Stem Cell and Regenerative Medicine |
Petek L.M.,Institute for Stem Cell and Regenerative Medicine |
Miller D.G.,Institute for Stem Cell and Regenerative Medicine |
Miller D.G.,University of Washington
Human Molecular Genetics | Year: 2015
Facioscapulohumeral muscular dystrophy (FSHD) is caused by chromatin relaxation that results in aberrant expression of the transcription factor Double Homeobox 4 (DUX4). DUX4 protein is present in a small subset of FSHD muscle cells, making its detection and analysis of its effects historically difficult. Using a DUX4-activated reporter,we demonstrate the burst expression pattern of endogenous DUX4, its method of signal amplification in the unique shared cytoplasm of the myotube, and FSHD cell death that depends on its activation. Transcriptome analysis of DUX4-expressing cells revealed that DUX4 activation disrupts RNA metabolismincluding RNA splicing, surveillance and transport pathways. Cell signaling, polarity and migration pathways were also disrupted. Thus, DUX4 expression is sufficient for myocyte death, and these findings suggest mechanistic links between DUX4 expression and cell migration, supporting recent descriptions of phenotypic similarities between FSHD and an FSHD-like condition caused by FAT1 mutations. © The Author 2015.
The recent findings should improve scientists' ability to use embryonic stem cells to grow new tissues and organs to replace those damaged by disease or injury. The findings also could lead to new treatments for common disorders ranging from infertility to cancer. The researchers reported on their study in the Nov. 16 issue of the journal Nature Cell Biology. After fertilization, a human egg begins to travel down the fallopian tube. As it does, it begins to divide to form a ball of embryonic cells. Each of these cells, called naive, pre-implantation embryonic cells, has the capacity to develop into any cell type in the human body, an ability called pluripotency. When the developing embryo enters the uterus, it must implant into the uterine lining if the pregnancy is to proceed. When this occurs, the naive stem cells undergo a critical change as they take the first step toward differentiating into specific cell types, such as gut, muscle or nerve cells. Such cells are called primed embryonic stem cells. "Implantation to mother's uterus is arguably one of the hardest things we ever have to do in life," said Ruohola-Baker, University of Washington professor of biochemistry and associate director of the UW Institute for Stem Cell and Regenerative Medicine, who led the research team. "In fact, most embryos fail to successfully implant and the pregnancy ends." Scientists in the field of tissue regeneration are particularly interested this shift. Although primed, post-implantation embryonic stem cells can still turn into any type of human cell, they are more difficult to work with than the pre-implantation, naive cells. To find out more about the differences between naive and primed pluripotent cells, the UW researchers first compared their gene expression profiles. This work, conducted by Yuliang Wang, now a senior research associate at Oregon Health & Science University, uncovered intriguing differences involving genes that affect the cells' metabolism. "The expression of the metabolic genes, particularly those related to the function of mitochondria, was much higher in the naive cells," Wang said. "There was also a big difference in gene expression of a specific enzyme called nicotinamide N-methyltransferase." To determine the effect of these changes, Henrik Sperber, a graduate student in the Ruohola-Baker laboratory, used a technique called mass spectroscopy to compare levels within cells of the metabolites. The approach, called metabolomic analysis, provides a 'chemical snapshot' that pictures in great detail what is going on within cells at a specific stage. Just by looking at the cells metabolomic profiles, researchers saw it was possible to distinguish between naive and primed pluripotent cells. The telltale metabolite that was found to be enriched in naive cells was methylnicotinamide, abbreviated MNA, a product of the metabolic enzyme whose levels increase in many cancers—nicotinamide N-methyltransferase, abbreviated NNMT. When active, NNMT consumes a methyl group from a compound called S-adenosyl methionine. This methyl group is normally used in a gene regulation process called epigenetic histone methylation. Without an adequate supply of the S-adenosyl methionine, regulation by histone methylation—and therefore correct gene expression—cannot take place. The researchers found that in the naive cells NNMT was active and behaved as a metabolic 'methyl-sink' by lowering the level of methyl groups available. It thereby limited gene repression by epigenetic histone methylation. In the primed cells, on the other hand, NNMT activity was low. As a result, S-adenosyl methionine was available for these epigenetic modifications that are required for a cell to enter the primed state. In fact, by knocking out specific genes through CRISPR gene-editing technology, Julie Mathieu, acting instructor in Ruohola-Baker laboratory, demonstrated that it was possible to stabilize the cells in either the primed or naive state by manipulating NNMT activity alone. "Our findings indicate that metabolites alone appear to be able drive many of the key changes in cellular function and differentiation," Ruohola-Baker said. "In addition to advancing our understanding of human embryonic development, the findings suggest we may be able to use metabolites, relatively simple compounds, to alter cell fate in the treatment of common disorders." For example, such an approach might eventually form the basis for treating the most common cause of infertility—the failure of the embryo to successfully implant—or for affecting the cellular changes that lead to the development of cancer. Explore further: New cell line should accelerate embryonic stem cell research More information: The metabolome regulates the epigenetic landscape during naïve-to-primed human embryonic stem cell transition, Nature Cell Biology, DOI: 10.1038/ncb3264
Palpant N.J.,Institute for Stem Cell and Regenerative Medicine |
Dudzinski D.,University of Washington
Gene Therapy | Year: 2013
Genetic engineering has emerged as a powerful mechanism for understanding biological systems and a potential approach for redressing congenital disease. Alongside, the emergence of these technologies in recent decades has risen the complementary analysis of the ethical implications of genetic engineering techniques and applications. Although viral-mediated approaches have dominated initial efforts in gene transfer (GT) methods, an emerging technology involving engineered restriction enzymes known as zinc finger nucleases (ZFNs) has become a powerful new methodology for gene editing. Given the advantages provided by ZFNs for more specific and diverse approaches in gene editing for basic science and clinical applications, we discuss how ZFN research can address some of the ethical and scientific questions that have been posed for other GT techniques. This is of particular importance, given the momentum currently behind ZFNs in moving into phase I clinical trials. This study provides a historical account of the origins of ZFN technology, an analysis of current techniques and applications, and an examination of the ethical issues applicable to translational ZFN genetic engineering in early phase clinical trials. © 2013 Macmillan Publishers Limited All rights reserved.
Sekeres M.A.,Cleveland Clinic |
Kantarjian H.,University of Texas M. D. Anderson Cancer Center |
Fenaux P.,Hematology Clinic Service |
Becker P.,Institute for Stem Cell and Regenerative Medicine |
And 6 more authors.
Cancer | Year: 2011
BACKGROUND: Romiplostim is a peptibody protein that augments thrombopoiesis by activating the thrombopoietin receptor. METHODS: In this phase 2, multicenter, open-label study, 28 thrombocytopenic patients with lower risk myelodysplastic syndromes (MDS) were assigned to receive romiplostim 750 lg administered subcutaneously either weekly or biweekly or administered as biweekly intravenous injections for 8 weeks. Patients also could enter a 1-year study extension phase. RESULTS: At least 1 adverse event was observed in 93% of patients. The most common adverse events were fatigue and headache (18% for both, and 5 events were grade 3 or 4. There was 1 serious treatment-related adverse event in the biweekly intravenous cohort (hypersensitivity). This hypersensitivity resolved without discontinuation of study treatment. No patients developed neutralizing antibodies or bone marrow fibrosis. Of the patients who completed 8 weeks of treatment, 57% had a complete platelet response, an additional 8% had a major platelet response, and 61% did not require a platelet transfusion during this period.Weekly subcutaneous injections achieved the highest mean trough concentrations. CONCLUSIONS: The safety and efficacy profiles of romiplostim in this study suggested that weekly subcutaneous administration of 750 μg romiplostim is an appropriate starting dose for future clinical studies in patients with MDS and thrombocytopenia. © 2010 American Cancer Society.
McMenamin S.K.,University of Washington |
Bain E.J.,University of Washington |
McCann A.E.,University of Washington |
Patterson L.B.,University of Washington |
And 7 more authors.
Science | Year: 2014
Pigment patterns are useful for elucidating fundamental mechanisms of pattern formation and how these mechanisms evolve. In zebrafish, several pigment cell classes interact to generate stripes, yet the developmental requirements and origins of these cells remain poorly understood Using zebrafish and a related species we identified roles for thyroid hormone (TH) in pigment cell development and patterning, and in postembryonic development more generally We show that adult pigment cells arise from distinct lineages having distinct requirements for TH and that differential TH dependence can evolve within lineages. Our findings demonstrate critical functions for TH in determining pigment pattern phenotype and highlight the potential for evolutionary diversification at the intersection of developmental and endocrine mechanisms.